We are transiting from BEND, OR to our lot in Indio, .CA. second leg of 3 took us from Sparks, NV to Ridgecrest, .CA. were in the mountains near Mammoth at about 7,800 ft elevation. Pulled into rest stop for a 15 minute break. Shut down engine. Fired back up and took off, continuing to climb. 20 seconds in rpms dropped in half, then immediately recovered. Three times in quick succession then recovered and ran like a top. 200 more miles and no issues. Any thoughts? Could elevation have played a part? Thanks. It's a C9S 425 turbo. Been reliable to date.